basic

Concrete Blocks Needed for a Wall Calculator

blocks = ceil(wall_area · waste / block_face_area).

Compute the number of concrete masonry units (CMU blocks) needed to build a wall, including a default 5-10 % waste factor for cuts and breakage. The standard 8 × 8 × 16 in CMU has a face area of 8 × 16 = 128 in² ≈ 0.888 ft², so a 100 ft² wall takes about 113 blocks plus waste.

Marcus Laurent By Marcus Laurent
Published Last reviewed 1 min read

Inputs

ft
ft
ft²
%

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

blocks = ceil(L · H · (1 + waste/100) / face_area).

In depth

Compute the number of concrete masonry units (CMU blocks) needed to build a wall, including a default 5-10 % waste factor for cuts and breakage. The standard 8 × 8 × 16 in CMU has a face area of 8 × 16 = 128 in² ≈ 0.888 ft², so a 100 ft² wall takes about 113 blocks plus waste.